Methods of Assessing the Energy Values of Foods for Ruminant Animals

Abstract

Assessment of energy value of foods 131of the same species? Two world wars have forced us to think of human beings and of farm animals as populations in a statistical sense. We count heads, assign 'man values' for energy requirements. Such a practice is essential for the administrator, but it does ignore individual differences. We have no evidence for variation in the efficiency of the fundamental biochemical processes with which individuals of the same species liberate energy from food. Yet human beings, as individuals, do differ in their instinctive demand for food. This difference is not necessarily correlated with the expenditure of energy. The obese human being within the nation is an inefficient individual. But the ox, fattening in his stall, is fulfilling his man-made destiny.The assessment of the energy value of human and animal foods cannot then be studied as a problem in pure chemistry. In due time biochemistry will elucidate the complexities of the processes at molecular and cellular level which determine the liberation of energy from food. But the final word is with the living animal itself which is a biological entity. And a human being is also a person.

The Effect of Pelleting and Wafering on the Feeding Value of Roughage—a Review*

“…Although grinding has been shown to increase roughage-cellulose digestibility in vitro (26), in only one in vivo digestion trial (74, 75) did grinding and pelleting increase crude-fibre digestibility. Dry-matter (or energy) digestibility was slightly increased by pelleting in five comparisons (2,3,56,71,74,75) but depressed in twenty-one other experiments (2,3,12,13,14,20,24,49,51,57,59,60,65,74,75,83,94,95,101,102). The mean change was a depression of 3-3 digestibility percentage units.…”

An automated multi‐calorimeter system: Preliminary experiments on laying hens

“…In many cases operation of a calorimeter and calculation of results are time-consuming, labour-intensive activities. Blaxter and Graham (1955) pointed out that the number of animals handled in most calorimetric balance experiments was too small for a statistical estimate of the errors to be made.…”

“…Workers have commented on the low productivity of direct and indirect calorimeters used for studies on energy metabolism (Blaxter and Graham, 1955;Hutchinson, 1955). Hutchinson (1955) attributed this to the great labour and expense of constructing and running a calorimeter.…”

Studies of grazing of crop forages by sheep

“…The use of feeding tables in reverse has probably been the method most frequently employed, but has several disadvantages. In particular, it is difficult to obtain valid and precise measures of weight gain during short feeding periods (Brown 1954), and the variation between different batches of the same forage species, or between animals, is ignored, whereas the weight of evidence points to substantial variation (Forbes 1936, Woodman et al (1937, Blaxter and Graham 1955). Furthermore, the application to free-grazing animals of maintenance requirements determined with sheep confined in respiration experiments is open to criticism.…”